Electronic apparatuses such as tablet terminals, smartphones, and mobile phones having a touch screen or a chassis may be provided with a haptic actuator that gives tactile feedbacks to the human body. A haptic actuator transmits a vibration to a vibrating body such as a touch screen or a chassis in response to an event generated by the system. A user perceives the vibration at the site with which the user has touched the vibrating body, or perceives the vibration as a sound. Haptic actuators, which use electric power as a driving source, can generally be characterized as an impact type or a vibration type, depending on the characteristics of the vibration.
Examples of the impact type haptic actuators include a shape memory metal impact actuator (SIA) that uses shape memory alloy. In the impact type haptic actuator, a vibration element strikes a vibrating body to provide a transient vibration. Examples of the vibration type haptic actuators include an eccentric rotating mass (ERM) actuator that uses an eccentric motor, a linear resonant actuator (LRA) that causes an alternating current to flow through a coil in a magnetic field to vibrate a movable element, and a piezoelectric actuator that uses a piezoelectric element. The vibration type haptic actuator gives a vibration of constant amplitude to a vibrating body for a predetermined time.
It will be convenient if haptic feedback can provide a set of perceptions having different characteristics according to the usage. For example, for a keystroke on a software keyboard, it is appropriate to give a strong, transient vibration that lasts a short time on the touch screen, so as to be able to address continuous keystrokes. For informing a user of an incoming mail or push notification from a website, it is appropriate to vibrate the chassis for a relatively long time enough for the user to notice it.
Currently, disposing both an impact type haptic actuator and a vibration type haptic actuator in a chassis of an electronic apparatus is disadvantageous from the space saving and cost saving standpoints.
Consequently, it would be preferable to provide an improved technique for generating haptic feedbacks for electronic apparatuses.